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From:Peter Zaitsev Date:January 16 2004 3:17am
Subject:Re: Is there a multi-user benchmark available
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On Thu, 2004-01-15 at 00:04, Yusuf Goolamabbas wrote:
> Hi, I want to compare the performance of Mysql 4.0.x on Linux 2.4.x
> machine with/without NPTL and on a Linux 2.6.x (with different io
> scheduler)


I've actually done this sort of benchmark. I however did not tested
stock 2.4.x kernel but  RH AS 3.0 one, this may explain results.

I used 2.6.0test9 kernel.

The results were what 2.6 was significantly slower than 2.4 (with
default IO scheduler). I was surprised in results but later saw the mail
in kernel list from some kernel developer telling what there are known
issues with 2.6 kernel default scheduler and database OLTP workloads.
This might be fixed already - I did test newer kernel.

The other interesting observation was significant benefit from using
O_DIRECT (I tested on RAID10 with 8 devices)

Speaking about NPTL - the results were sort of upsetting. On moderate
amount of threads (500-1000)  NPTL showed worse performance compared to
LinuxThreads.  The largest problem was  NPTL results were rather
unstable -  2  sequential test runs (10min each) showed  could show
results  being order of magnitude different, even for completely memory
load workloads which expected to be very stable.

The difference could be seen even running VMSTAT - in some cases NPTL
executed healthily, having good CPU usage in user area, while sometimes
it went to 99% in system area having small progress from user side.

The synthetic benchmarks I've run however showed NPTL having lesser cost
of pthread_* functions.

It could be however also related to system I used  4Way Intel Xeon w HT

It would be great if you could run your tests to see if you get any
different results. 

I've used my special "investigation" tool for this benchmark which is
not very user friendly, so we did not publish it.  I can send you
however together with instructions if you're interested.

> Is there a multi-user version of a mysql benchmark available ?
> Has anybody done something similar to what I have described above ?

There is OSDB ( you could try.

We have several multi user benchmarks in works but unfortunately none of
them are reached the stage to be published yet.

We have AS3AP Perl implementation as well as MySQL port of OSDL DBT2
benchmark which are both to be released soon. 

Peter Zaitsev, Full-Time Developer

Want to swim with the dolphins? (April 14-16, 2004)

Is there a multi-user benchmark availableYusuf Goolamabbas15 Jan
  • Re: Is there a multi-user benchmark availablePeter Zaitsev16 Jan
    • Re: Is there a multi-user benchmark availableYusuf Goolamabbas16 Jan